To begin with, heat 1 tablespoon oil in a pan.
While the oil is heating, add cumin seeds and allow it to crackle.
Then, add chopped green chillies and fry for another few seconds
After the cumin and green chillies releases its aroma, then add chopped onions and fry until soft and pink.
Once the onions turns pink and raw smell goes off, take it off the heat, Then, allow it to cool completely.
As the onions cools off, in a large, add boiled potatoes. Along with potatoes, add corinader leaves, mint leaves, coriander seeds, garam masala powder, chaat masala, salt and cooled onion chilli mixture.
Combine everything together very well to form the stuffing of the bread roll. Then, divide the stuffing into equal small lemon sized balls.